Combination capillary tube and bulb and method of making same



1939; F. w. SULLIVAN 2,170,612

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' Filed Feb. 19, 1938 riravzczz's W'JZaIZZ'r aa A TTORNEYS Patented Aug. 22, 1939 COIMBINATION CAPILLARY TUBE AND AND METHOD OF MAKING SAME Francis W. Sullivan, Cranstou, B... L, assignor' to United Wire & Supply Corporation, a corporation of Rhode Island Application February 19, 1938, Serial No. 191,427

2 Claims. (Ci. 29-1482) 6 provision of such a unit having a capillary tube and a bulb in which a deoxidized and dehydrated surface is presented at the joint between the capillary tube and the bulb. 7

Another object of the invention is to eliminate 10 the necessity of soldering or securing together a capillary tube and bulb by users of such units previously formed by the assembly.

Another object of the invention is to provide the capillary tube and bulb of a single piece of material that leakages or other undesirable effects by reason of a joint between the tube may be completely eliminated.

With these and other objects in view, the invention consists of certain novel features of construction, as will be more fully described, and

particularly pointed out in the appended claims. In the accompanying drawing: Fig. 1 is a side elevation of a coil of a capillary tube with a bulb at one end thereof; Fig. 2 is an end view of this unit;

Fig. 3 is a sectional view of the bulb and capil lary tube. Prior to the advent of this invention it was usual practice where thermostatic controls were used and a capillary tube and bulb were required that the two be assembled by inserting the capillary-tube within the bulb or .by reducing the end of the bulb and securing the capillary tube to it either by solder, brazing or some means requiring the use of heat. In the refrigerating industry it is highly desirable to have the inner surface of the container for the expansible liquid deoxidized and dehydrated in order to prevent undesirable chemical actions taking place on these contacted surfaces. The heating for joining of the bulb and capillary tube destroyed this chemically treated surface at the joint and thus provided a unit imperfect in this respect; and in order to avoid this imperfection I have made the bulb and capillary portions from a single piece of material with the deoxidized and dehydrated finish uninterrupted by anf'joint or any oxidized surface at the joint on the inner portion of the tubular conduit; and the following is a more deso tailed description of the present embodiment of this invention, illustrating the preferred means by which these advantageous results may be accomplished.

The portion of tubing'ifl is of the desired size which I require for the bulb of the unit which I produce. The tubing is of this diameter through- 5 out its length at the commencement of the formation of the unit and is reduced in diameter as by drawing down to provide a capillary portion H. In drawing, I stop the drav. mechanism after the length II is drawn as far as the portion :0

I2 and then reverse the drawing machine to pass the portion H in the opposite direction through the die, this being repeated in other dies until the required small daimeter H is of a capillary size on its inner surface It. it

The inner surface of the entire length of the unit in both portions l0 and n is deoxldized and dehydrated after the drawing process and then a coil is provided as at H for convenient shipping or .for use in this form if desired oi' the U the capillary tube II and the bulb II where the greater amount of liquid is stored for changing its volume due to heat conditions and accordingly 85 the deoxidized and dehydrated finish of the inner surface of the material throughout its length is maintained.

The foregoing description is directed solely towards the construction illustrated, but I desire 30 it to be understood that I reservethe privilege of resorting to all the mechanical changes to which the device is susceptible, the invention being defined and limited only by the terms of the appended claims. 7 1 85 I claim:

. 1. Acapillary tube. and bulb .for thermostatic control comprising a length of tube of one diameter and a continuing length of larger diameter formed as a single piece therewith, said tube 40 having along its entire length a deoxidized and dehydrated surface uninterrupted at the juncture of the two diameters.

2. The method of forming a capillary tube and bulb for a thermostatic control which consists 46' in reducing the diameter of a tube of relatively large size for a portion of its length to capillary size leaving the other portion larger, and deoxidizing and dehydrating the inner surface 01' the unit so formed for its entire length. 50

' FRANCIS W. SUILIVAN. 

